This invention relates to agricultural balers and more particularly to so-called round balers which produce cylindrical bales or rolls of crop material.
In general, round balers are of two types: the expanding chamber type which produces bales with a relatively hard core and a generally high and relatively constant density throughout; and the fixed chamber type which produces bales with a relatively soft core but a relatively compacted or hard outer layer or shell.
The advantages of expanding chamber balers are that they pack more crop material into a bale compared with a similarly sized soft core bale, and they can produce bales of any size up to the maximum which a given machine is capable of producing, with all sizes of bales being in generally good order from the standpoint of being subjected to handling without falling apart. The advantages of fixed chamber balers are that they produce bales with a reduced tendency to molding if the crop material is baled wet and the soft bale core presents no problems to cattle when feeding from the bale, whereas hard bale cores can be difficult to tear apart. Fixed chamber balers produce with good weathering characteristics due to the hard shell, which ensures a bale which is very stable when being handled. Fixed chamber balers are of relatively simple design and they normally have no difficulty in forming a bale core which can sometimes be a problem with expanding chamber balers when handling short lengths of crop material.
U.S. Pat. No. 4,182,101 discloses a round baler of the expanding chamber type which has a single endless web in the form of a series of side-by-side belts extending around a plurality of rollers to define a vertically disposed bale starting chamber. One of the rollers is supported by a pair of arms that are pivotally mounted to the side walls of the baler. Springs are provided to normally urge the arms in a downward direction to maintain tension in the belts.